The table below has been adapted from ‘RICS Whole life carbon assessment for the built environment by iStructE’ and details the project life cycle and carbon categories through four stages: product (and materials), construction process, use and end of life.

Figure 1: IStructE, A brief guide to calculating embodied carbon 

Key terms: 

- Embodied carbon (to practical completion) refers to stages A1-A5, and includes emissions associated with the product/material manufacturing, transport and installation for a construction project.

- Embodied carbon (over the life cycle) refers to stages A1–A5, B1–B5 and C1–C4, and includes the above emissions sources plus product/material use, maintenance, repair, replacement and refurbishment, and end of life.

- Whole life carbon refers to all stages (including B6 &B7) and includes the above plus operational energy and water use.

Recent analysis by Robertson alongside industry leading research has shown that the embodied carbon of materials and products over the life cycle can account for around 60-70% of whole life carbon.

Figure 2: LETI, Climate Emergency Design Guide  

Robertson uses the UK Green Building Council’s ‘Net Zero Carbon Buildings: A Framework Definition’ reporting process to focus on quantification of our actions and choices that can reduce whole life carbon.

We have extended our drive to reduce carbon by working closely with our customers, design teams and supply chain to reduce the embodied carbon of our projects wherever possible. We also engage with a range of built environment best practice working groups to support the industry to continue to lower emissions.

Case study: Merkinch Primary School and Family Centre, Inverness 

The new Merkinch Primary is the largest school in Scotland to be built using a cross laminated timber frame (CLT), more sustainable than traditional methods of construction.

We used 'OneClick LCA' whole life carbon calculation software to quantify the carbon impact of key changes and initiatives, and capture the whole life carbon for the new school and family centre.

We reduced whole life carbon by 60% – compared with the original design – by using cross laminated timber frame (CLT) in place of the proposed, more traditional steel frame with concrete infill panels. This resulted in lighter foundations (supporting reduced embodied carbon), an improved project programme, better thermal performance, and a superior internal environment.

Merkinch Primary School and Family Centre project generated 437 kgCO2e/m2 of embodied carbon over the life cycle.

The RIBA Sustainable Outcomes Guide specifies Climate Challenge target metrics for non-domestic buildings for embodied carbon over the life cycle which are increasingly challenging as we approach 2030:

Generating just 437 kgCO2e/m2 of embodied carbon over the life cycle highlights our successful best practice approach to the project as we work towards net zero carbon, and provides a modern school for future generations of pupils.

Merkinch Primary School